The invention concerns a method and means of removing sediments (particles) from a fluid after deposition.
The invention can be used for the extraction of sediments from rivers carrying sediments in suspension, so as to control the processes on the river bed or utilize such sediments for a variety of purposes including: sand and gravel extraction, earth filling, mineral exploration, or the measurement of sediment-transport in rivers.
A specific application of the invention is as a water outlet in river development systems and associated constructions such as hydropower stations, irrigation systems and normal water supply where there is a need to remove sediments in the river water before it is led into the pipelines, tunnels or channels that connect the river to the end user.
Known means of removing sediments from systems which are in continuous operation involve flushing, suction or the mechanical scraping of sediments. Flushing (continuous or periodic) is dependent on obtaining sufficient velocity in the fluid carrying the particles to force the particles out of the fluid stream by means of a flushing device. Despite the substantial fluid consumption, the method produces a correspondingly low concentration of sediments in the flushed outflow. If it is required to separate particles of different sizes, their physical characterists will lead to deposition in different geographical areas of the sedimentation basin. This involves a further increase in the fluid requirements of such flushing systems.
Systems involving the suction of deposited sediments will often prove expensive in operation both because of the machinery involved and the cost of its maintenance.
The removal of deposited sediments from settlement basins can either be done by closing and draining the basin, or while the system is operational.
After drainage, the sediments can either be removed by flushing or mechanical means whilst the rest of the system has been made inoperative. In practical terms this is an extremely costly and inappropriate method, where the operating losses will be enormous.